METHOD AND DEVICE FOR HEATING AND/OR DRYING WITH AN MHF-FIELD OF POWDERY, GRANULAR AND/OR PASTY MATERIALS IN A CONICAL MIXING VESSEL

摘要

Method and device for heating and/or drying of powdery, grainy and/or pasty materials with an MHF-field in a conical mixing vessel (2) having a vertical axis, which vessel narrows in a downward direction, and in which the material is mixed by at least one mixing screw (3) making a rotary movement around its axis and a revolving movement parallel to the innerside of the mixing vessel (1), whereas the material to be heated and/or dried is irradiated by at least one HF-field. The invention is characterized by radiating an MHF- or RF-field substantially completely inside the material to be heated and/or dried, which field has a frequency of 10 to 50 MHz, preferably 27 MHz, and is rotated around the vertical symmetry axis of the vessel (2) with the same rotation speed as the revolving speed of the mixing screw (3). The impedance of the antenna (4) for the MHF-field is preferably automatically adapted to the alteration of the impedance of the material to be heated and/or dried.